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Ch.21 - Transition Elements and Coordination Chemistry
McMurry - Chemistry 8th Edition
McMurry8th EditionChemistryISBN: 9781292336145Not the one you use?Change textbook
All textbooksMcMurry 8th EditionCh.21 - Transition Elements and Coordination ChemistryProblem 21.90
Chapter 21, Problem 21.90

Draw all possible diastereoisomers of [Cr(C2O4)2(H2O)2]-. Which can exist as a pair of enantiomers?

Verified step by step guidance
1
Identify the coordination geometry of the complex. Chromium(III) typically forms octahedral complexes.
Determine the ligands and their arrangement. The complex has two oxalate (C_2O_4) ligands and two water (H_2O) molecules.
Consider the possible arrangements of the ligands around the chromium center. The oxalate ligands can be either cis (adjacent) or trans (opposite) to each other.
Draw the possible isomers: For the cis arrangement, the two water molecules are adjacent, and for the trans arrangement, they are opposite.
Identify which isomers can exist as enantiomers. Only the cis isomer can have non-superimposable mirror images, making it capable of existing as a pair of enantiomers.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Diastereoisomers

Diastereoisomers are stereoisomers that are not mirror images of each other. They occur in molecules with multiple chiral centers, where at least one but not all chiral centers differ in configuration. Understanding diastereoisomers is crucial for analyzing the spatial arrangement of ligands around a central atom, particularly in coordination compounds like the one in the question.

Chirality and Enantiomers

Chirality refers to the property of a molecule that makes it non-superimposable on its mirror image, leading to the formation of enantiomers. Enantiomers are pairs of chiral molecules that are mirror images of each other and have identical physical properties except for their interaction with polarized light. Identifying which diastereoisomers can exist as enantiomers is essential for understanding the optical activity of the compound.
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Drawing Enantiomers

Coordination Chemistry

Coordination chemistry studies the structures and properties of complex compounds formed by metal ions and ligands. The geometry of these complexes, such as octahedral or tetrahedral arrangements, influences their stereochemistry and the potential for isomerism. In the context of the question, recognizing the coordination environment of chromium and the arrangement of oxalate and water ligands is vital for determining possible diastereoisomers.
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Related Practice
Textbook Question

Based on effective nuclear charge (Zeff), which ion is the strongest oxidizing agent? 

(a) Cu2+

(b) Ni2+

(c) Fe2+

(d) Mn2+

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Textbook Question

The [Cr(H2O)6]3+ ion is violet, and [Cr(CN)6]3- is yellow. Explain this difference using crystal field theory. Use the colors to order H2O and CN- in the spectrochemical series.

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Textbook Question

The glycinate anion, gly-= NH2CH2CO2 -, bonds to metal ions through the N atom and one of the O atoms. Using to represent gly-, sketch the structures of the four stereoisomers of Co(gly)3.

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Textbook Question

What is the oxidation state of the metal in each of the complexes?

a. [Ni(CN)5]3–

b. Ni(CO)4

c. [Co(en)2(H2O)Br]2+

d. [Cu(H2O)2(C2O4)2]2–

e. Co(NH3)3(NO2)3

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Textbook Question

Which of the following complexes can exist as diastereoisomers?

 

(a) [Cr(NH3)2Cl4]-

(b) [Co(NH3)5Br]2+

(c) [MnCl2Br2]2- (tetrahedral)

(d) [Pt(NH3)2Br2]2-

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Textbook Question

Predict the number of unpaired electrons for each of the following. 

(c) Zn2+

(d) Cr3+

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